Screw assembly and washing machine using the same

ABSTRACT

A screw assembly and a washing machine using the same are disclosed. The screw assembly includes a head, to be seated on an upper surface of the rotated member, a body, extending downwardly from the head, to be screwed into the rotating member and to thereby grip the rotated member between the head and the rotating member, and a pillar, formed on an upper surface of the head, having an outer perimeter for being gripped by a first tool, the pillar having a groove for receiving a second tool. The screw assembly may include an inner tub having a bottom surface, wherein the pulsator is to be gripped to the bottom surface of the inner tub.

This application claims the benefit of Korean Application Nos. P2003-072637 and P2003-072638, both filed on Oct. 17, 2003, which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a pulsator washing machine, and more particularly, to a screw assembly and a washing machine using the same, wherein the screw assembly is used for coupling a pulsator to a drive shaft of a washing machine.

2. Discussion of the Related Art

Generally, a washing machine is an apparatus to remove contaminants from laundry by applying an energy such as impact or the like. According to the method of applying energy, the washing machines are classified into pulsator washing machines, drum washing machines, and agitator washing machines.

In the drum washing machine, laundry is dropped, impacted and washed by the rotation of the drum. In the pulsator washing machine, contaminants are removed by water current generated by rotation of a drive shaft vertically installed in an inner tub, which drives a pulsator coupled to the drive shaft. In the agitator washing machine, contaminants are removed by water current generated by rotation of an agitator coupled with a drive shaft vertically installed in an inner tub.

Referring to FIG. 1, a conventional pulsator washing machine includes a main body 10, an outer tub 20, an inner tub 30, a pulsator 40, a motor 50, and a drive shaft 60. The main body 10 constitutes the appearance of the washing machine and is made up of several component parts installed. The outer tub 20 is installed inside the main body 10 and stores washing water. The inner tub 30 is rotatably installed inside the outer tub 20 and accommodates laundry therein. The pulsator 40 is rotatably installed inside the inner tub 30 to create a water current during its rotation. The motor 50 is installed below the outer tub 20 to rotate the inner tub 30 and the pulsator 40. The drive shaft 60 has one end coupled to the motor 50 and the other end coupled to the inner tub 30 and the pulsator 40. The drive shaft 60 transfers a power generated by the motor 50 to the inner tub 30 and the pulsator 40.

FIG. 2 illustrates a coupling structure of the pulsator 40 and the inner tub 30, whereby the pulsator is secured in the bottom of the inner tub by a screw 70, which is typically a right-handed screw, i.e., tightened by a clockwise rotation. Meanwhile, however, the pulsator 40 rotates in both the forward and reverse directions, and when the pulsator rotates in the releasing direction of the screw 70, the screw tends to loosen. Therefore, the pulsator 40 cannot be reliably fixed to the drive shaft 60. In addition, if, in tightening the screw 70, excessive force is applied to couple the pulsator 40 to the drive shaft 60, a screwdriver may fail to remove the screw.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a screw assembly and a washing machine using the same that substantially obviate one or more problems due to limitations and disadvantages of the related art.

An object of the present invention is to provide a screw assembly and a washing machine using the same, wherein the screw assembly resists loosening during normal pulsator operation.

Another object of the present invention is to provide a screw assembly and a washing machine using the same, wherein the screw assembly prevents a failure of the screw assembly to be released using a screwdriver.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, a screw assembly for fixing a rotated member to a rotating member for driving the rotated member includes a head, to be seated on an upper surface of the rotated member, a body, extending downwardly from the head, to be screwed into the rotating member and to thereby grip the rotated member between the head and the rotating member, and a pillar, formed on an upper surface of the head, having an outer perimeter for being gripped by a first tool, the pillar having a groove for receiving a second tool.

The screw assembly may include an inner tub having a bottom surface, wherein the pulsator is to be gripped to the bottom surface of the inner tub. The outer perimeter of the pillar may have a polygonal shape. And, the polygonal shape of the pillar may be a hexagon. The groove may be formed in a top surface of the pillar and may have at least one slot for receiving the second tool. The rotated member may be a pulsator of a washing machine, and the rotating member may be a drive shaft coupled to a motor for driving the pulsator.

In another aspect of the present invention, a screw assembly for fixing a rotated member to a rotating member for driving the rotated member includes a screw including a head, to be seated on an upper surface of the rotated member, a body, extending downwardly from the head, to be screwed into the rotating member and to thereby grip the rotated member between the head and the rotating member, and a plurality of protrusions formed on a lower surface of the head, and a washer, encircling the body and positioned below the head, having at least one fin for catching on one of the plurality of protrusions when the screw is rotated in a releasing direction.

Each protrusion may include two exposed surfaces, one exposed surface being a leading surface facing opposite the releasing direction of the screw and the other exposed surface being a trailing surface facing the releasing direction of the screw, the leading surface of each protrusion having an inclined surface. And, each protrusion may include two exposed surfaces, one exposed surface being a leading surface facing opposite the releasing direction of the screw and the other exposed surface being a trailing surface facing the releasing direction of the screw, the trailing surface of each protrusion being substantially perpendicular to the lower surface of the head.

When the screw is tightened, the at least one fin may be temporarily deformed to allow the protrusions to pass over the washer. Herein, the at least one fin may have a first surface for preventing the screw from being released when the rotated member is rotated in the releasing direction of the screw. And, the at least one fin may have a second surface, bent with respect to the first surface, to be deflected by the protrusions when the screw is rotated in a tightening direction. The washer may be formed to receive the lower surface of the head. And, the lower surface of the head may be conic in shape. The screw assembly may include a pillar, formed on an upper surface of the head, having an outer perimeter for being gripped by a first tool.

In another aspect of the present invention, a washing machine includes a pulsator, a drive shaft for driving the pulsator, a screw including a head seated on an upper surface of the pulsator, a body, extending downwardly from the head, screwed into the drive shaft and thereby gripping the pulsator between the head and the drive shaft, and a plurality of protrusions formed on a lower surface of the head, a washer, encircling the body and positioned below the head, having at least one fin for catching on one of the plurality of protrusions when the screw is rotated in a releasing direction, and a pillar, formed on an upper surface of the head, having an outer perimeter for being gripped by a first tool, the pillar having a groove for receiving a second tool. The washing machine may include an inner tub having a bottom surface, wherein the pulsator is gripped to the bottom surface of the inner tub.

In a further aspect of the present invention, a washing machine includes a cabinet, an outer tub disposed inside the cabinet, an inner tub rotatably installed inside the outer tub, a pulsator fixed with respect to the inner tub, drive means for rotating the pulsator and inner tub via a shaft coupled to the pulsator, and a screw for coupling the pulsator to the shaft, the screw including a head seated on an upper surface of the pulsator, a body, extending downwardly from the head, screwed into the drive shaft and thereby clamping the pulsator between the head and the drive shaft, and a plurality of protrusions formed on a lower surface of the head.

The screw assembly may include a washer, encircling the body and positioned below the head, having at least one fin for catching on one of the plurality of protrusions when the screw is rotated in a releasing direction. And, each protrusion may include two exposed surfaces, one exposed surface being a leading surface facing opposite the releasing direction of the screw and the other exposed surface being a trailing surface facing the releasing direction of the screw, the leading surface of each protrusion having an inclined surface and the trailing surface of each protrusion being substantially perpendicular to the lower surface of the head.

It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiments of the invention and together with the description serve to explain the principle of the invention. In the drawings:

FIG. 1 is a sectional view of a conventional pulsator washing machine;

FIG. 2 is a breakaway perspective view of a coupling structure of the pulsator washing machine of FIG. 1;

FIG. 3 is a perspective view of a screw assembly according to a first embodiment of the present invention;

FIG. 4 is a breakaway perspective view of a screw assembly according to a second embodiment of the present invention; and

FIG. 5 is a detailed partial view of the washer of FIG. 4.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.

FIG. 3 illustrates a screw assembly 100 used for fixing a pulsator of a washing machine according to a first embodiment of the present invention, in which an outer perimeter of the screw assembly is gripped for rotation of the screw assembly. The screw assembly 100 includes a head 110, a body 120, and a pillar 130. The screw assembly 100 is passed through a center portion of the pulsator, to fix the pulsator to a drive shaft. The head 110 is a circular plate having a larger diameter than the body 120 and shaped as a cone whose diameter diminishes downward to the body 120. Accordingly, though the characteristic features of the present invention may be applied to a pan head screw, the screw assembly 100 of the present invention is essentially formed as a flat head screw, whereby the central hole of the pulsator has an angular (or conic) recess for receiving the head of the screw.

The body 120 extends downward from the head 110 and is shaped as a cylindrical rod. Also, the body 120 passes through the pulsator to be coupled to the drive shaft. To fix the pulsator to the drive shaft using the screw assembly 100, the head 110 is provided with the pillar 130 whose outer perimeter is gripped by a tool, such as a wrench. To assist in the relation of the pillar 130, the pillar 130 has an angular outer perimeter. In more detail, the pillar 130 is shaped as a polygonal pillar, and more preferably, as a hexagonal pillar.

Also, the pillar 130 is smaller than the head 110 and has a groove 140 formed at its top surface. The groove has at least one slot such that a tool (e.g., a screwdriver) can be inserted into the slot. The groove 140 preferably consists of the crossing slots of a Philips head screw.

The screw assembly 100 can be rotated to couple the pulsator to the drive shaft, using another tool (e.g., a wrench) as an alternative to the screwdriver. By using a tool capable of gripping the outer perimeter of the pillar 130 with a greater gripping force, the pulsator can be more easily separated from the drive shaft. The groove of the screw assembly 100 may be shaped as a polygonal groove for receiving a correspondingly shaped tool (e.g., an allen wrench).

FIGS. 4 and 5 show a screw assembly 100 according to a second embodiment of the present invention, in which the screw assembly tends to maintain its tightened state even when the pulsator rotates in opposition to the tightening direction of the screw assembly. The screw assembly of the second embodiment includes a plurality of protrusions 150 formed on a lower surface of a head 110′ to engage with a washer 160.

The plurality of protrusions 150 is disposed on the lower surface of the head 110′, i.e., on an inclined surface of the head 110′, at a predetermined interval. The protrusions 150 extend toward a center of the screw assembly 100 from an outer circumference of the head 110′.

The protrusions 150 are formed to minimize friction when the screw is tightened. To this end, each of the protrusions 150 has an inclined surface 151 of which height is reduced as it goes to the tightening direction of the screw. In FIG. 5, the tightening direction of the screw is a direction indicated by an arrow.

The protrusions 150 are formed such that though the screw assembly 100 rotates in the releasing direction, the screw assembly 100 should not be released. Accordingly, in each of the protrusions 150, a surface 152 positioned in the releasing direction of the screw is perpendicular to the head 110′. More specifically, in the plurality of protrusions 150, one surface 151 is inclined to the head 110′ and the other surface 152 is perpendicular to the head 110′.

In the screw assembly 100, the washer 160 is positioned below the head 110′. The washer 160 is formed from a circular plate having a hole through which the body 120 is passed. Also, the inner and outer circumferences of the washer 160 are inclined at an angle equal to the lower surface of the head 110′, which has a conic shape, such that the washer 160 corresponds to the lower surface of the head 110′.

Also, the washer 160 has a plurality of fins 165 formed on the outer circumference thereof. The fins 165 cause the screw to be latched while the screw rotates in the releasing direction, thereby preventing the screw from being released. Each of the fins 165 has a bent surface 165 b such that when the screw assembly is tightened, the protrusions 150 pass over the washer 160 smoothly. Each of the fins 165 has a flat surface 165 a supporting the protrusions 150, so as to prevent the screw assembly from being released when the pulsator reversely rotates.

In more detail, the plurality of fins 165 are formed on the outer circumference of the washer 160. The plurality of fins 165 are respectively inserted into the plurality of protrusions 150 and are in close contact with the head 110′. The bent surface 165 b of each of the fins 165 is in contact with the inclined surface 151 of each of the protrusions 150, and one end of each of the fins 165 is latched by the perpendicular surface 152 of each of the protrusions 150. Also, for close contact between the screw assembly 100 and the pulsator, the screw assembly 100 may further include a rubber ring 170.

To couple the screw assembly 100 to the pulsator, the washer 160 and the rubber ring 170 are first inserted onto the body 120. Thereafter, the screw assembly 100 is inserted into the center of the pulsator and is screwed with the pulsator, thereby fixing the pulsator to the drive shaft. In fixing the pulsator to the drive shaft, the protrusions 150 and the fins 165 are slid along their inclined surfaces and do not substantially hinder the tightening of the screw assembly 100. When the pulsator rotates in opposition to the tightening direction of the screw assembly 100, the screw assembly is released. However, the washer 160 and the fins 165 support the protrusions 150 of the screw assembly 100, thereby preventing the screw assembly from being released. More specifically, leading edges of the flat surface 165 a of the fins 165 support the perpendicular surfaces 152 of the protrusions 150, thereby preventing the screw assembly 100 from being released.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents. 

1. A screw assembly for fixing a rotated member to a rotating member for driving the rotated member, the screw assembly comprising: a head, to be seated on an upper surface of the rotated member; a body, extending downwardly from the head, to be screwed into the rotating member and to thereby grip the rotated member between the head and the rotating member; and a pillar, formed on an upper surface of the head, having an outer perimeter for being gripped by a first tool, the pillar having a groove for receiving a second tool.
 2. The screw assembly as claimed in claim 1, wherein the outer perimeter of the pillar has a polygonal shape.
 3. The screw assembly as claimed in claim 2, wherein the polygonal shape of the pillar is a hexagon.
 4. The screw assembly as claimed in claim 1, wherein the groove is formed in a top surface of the pillar.
 5. The screw assembly as claimed in claim 4, wherein the groove has at least one slot for receiving the second tool.
 6. The screw assembly as claimed in claim 1, wherein the rotated member is a pulsator of a washing machine and the rotating member is a drive shaft coupled to a motor for driving the pulsator.
 7. The screw assembly as claimed in claim 6, further comprising an inner tub having a bottom surface, wherein the pulsator is to be gripped to the bottom surface of the inner tub.
 8. A screw assembly for fixing a rotated member to a rotating member for driving the rotated member, the screw assembly comprising: a screw, including: a head, to be seated on an upper surface of the rotated member; a body, extending downwardly from the head, to be screwed into the rotating member and to thereby grip the rotated member between the head and the rotating member; and a plurality of protrusions formed on a lower surface of the head; and a washer, encircling the body and positioned below the head, having at least one fin for catching on one of the plurality of protrusions when the screw is rotated in a releasing direction.
 9. The screw assembly as claimed in claim 8, wherein each protrusion comprises two exposed surfaces, one exposed surface being a leading surface facing opposite the releasing direction of the screw and the other exposed surface being a trailing surface facing the releasing direction of the screw, the leading surface of each protrusion having an inclined surface.
 10. The screw assembly as claimed in claim 8, wherein each protrusion comprises two exposed surfaces, one exposed surface being a leading surface facing opposite the releasing direction of the screw and the other exposed surface being a trailing surface facing the releasing direction of the screw, the trailing surface of each protrusion being substantially perpendicular to the lower surface of the head.
 11. The screw assembly as claimed in claim 8, wherein, when the screw is tightened, the at least one fin is temporarily deformed to allow the protrusions to pass over the washer.
 12. The screw assembly as claimed in claim 8, wherein the at least one fin has a first surface for preventing the screw from being released when the rotated member is rotated in the releasing direction of the screw.
 13. The screw assembly as claimed in claim 8, wherein the at least one fin has a second surface, bent with respect to the first surface, to be deflected by the protrusions when the screw is rotated in a tightening direction.
 14. The screw assembly as claimed in claim 8, wherein the washer is formed to receive the lower surface of the head.
 15. The screw assembly as claimed in claim 8, wherein the lower surface of the head is conic in shape.
 16. The screw assembly as claimed in claim 15, further comprising a pillar, formed on an upper surface of the head, having an outer perimeter for being gripped by a first tool.
 17. The screw assembly as claimed in claim 16, wherein the outer perimeter of the pillar has a polygonal shape.
 18. The screw assembly as claimed in claim 17, wherein the polygonal shape of the pillar is a hexagon.
 19. The screw assembly as claimed in claim 18, wherein the pillar has a groove for receiving a second tool.
 20. The screw assembly as claimed in claim 8, wherein the groove has at least one slot for receiving the second tool.
 21. A washing machine, comprising: a pulsator; a drive shaft for driving the pulsator; a screw, including: a head seated on an upper surface of the pulsator; a body, extending downwardly from the head, screwed into the drive shaft and thereby gripping the pulsator between the head and the drive shaft; and a plurality of protrusions formed on a lower surface of the head; a washer, encircling the body and positioned below the head, having at least one fin for catching on one of the plurality of protrusions when the screw is rotated in a releasing direction; and a pillar, formed on an upper surface of the head, having an outer perimeter for being gripped by a first tool, the pillar having a groove for receiving a second tool.
 22. The washing machine as claimed in claim 21, further comprising an inner tub having a bottom surface, wherein the pulsator is gripped to the bottom surface of the inner tub.
 23. A washing machine, comprising: a cabinet; an outer tub disposed inside the cabinet; an inner tub rotatably installed inside the outer tub; a pulsator fixed with respect to the inner tub; drive means for rotating the pulsator and inner tub via a shaft coupled to the pulsator; and a screw for coupling the pulsator to the shaft, the screw including: a head seated on an upper surface of the pulsator; a body, extending downwardly from the head, screwed into the drive shaft and thereby clamping the pulsator between the head and the drive shaft; and a plurality of protrusions formed on a lower surface of the head.
 24. The washing machine as claimed in claim 23, wherein the screw assembly further comprises a washer, encircling the body and positioned below the head, having at least one fin for catching on one of the plurality of protrusions when the screw is rotated in a releasing direction.
 25. The washing machine as claimed in claim 24, wherein each protrusion comprises two exposed surfaces, one exposed surface being a leading surface facing opposite the releasing direction of the screw and the other exposed surface being a trailing surface facing the releasing direction of the screw, the leading surface of each protrusion having an inclined surface and the trailing surface of each protrusion being substantially perpendicular to the lower surface of the head. 